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While there are a few risk factors for dementia that you can’t control — like age and family history — a growing body of research shows that there are several that can potentially be changed

throughout life. And a recent study suggests that three of these so-called modifiable risk factors may have a big impact on an aging brain.

Diabetes, alcohol consumption (measured by frequency) and exposure to air pollution are the most harmful modifiable risk factors for dementia out of 15 that were studied in a recent report

published in the journal Nature Communications. A team of researchers examined brain scans of nearly 40,000 UK Biobank participants and found that parts of the brain associated with

Alzheimer’s disease, the most common form of dementia, that are more prone to earlier and accelerated aging were most affected by these three factors.

“We know that a constellation of brain regions degenerates earlier in aging, and in this new study we have shown that these specific parts of the brain are most vulnerable to diabetes,

traffic-related air pollution — increasingly a major player in dementia — and alcohol, of all the common risk factors for dementia,” study coauthor Gwenaëlle Douaud, an associate professor

at the University of Oxford, said in a statement.

Other known modifiable risk factors studied were blood pressure, cholesterol, weight, smoking, depression, inflammation, hearing, sleep, socialization, diet, physical activity and

education.

The study findings are not surprising, says Andrew Bender, a neuroimaging researcher at the Cleveland Clinic Lou Ruvo Center for Brain Health. 

Excessive alcohol use — defined as more than 21 drinks weekly — is among the 12 modifiable risk factors for dementia noted in a 2020 report published by the Lancet Commission. The Centers

for Disease Control and Prevention (CDC) says that over time, too much alcohol can lead to learning and memory problems, including dementia.

And Bender, who was not involved in the latest study, says “diabetes is a really well studied and well known risk factor.” If diabetes is not well controlled and too much sugar remains in

the blood, it can damage the organs over time, including the brain, explains the Alzheimer’s Association. High blood sugar is also linked to inflammation and cardiovascular disease — both of

which can contribute to declining brain health.

Research on the health effects of air pollution is newer, but has been accumulating in recent years. A 2023 study published in JAMA Internal Medicine looked at data from more than 27,000

adults older than 50 and found that those who went on to develop dementia were more likely to live in places with higher levels of fine particulate matter. This type of air pollution can

come from vehicles and factories, though in this particular study, fine particulate matter from agriculture and wildfires was specifically associated with an increased risk of dementia.

Long-term exposure to wildfire smoke seems to be especially bad for brain health, according to a 2024 study published in the journal JAMA Neurology. A team of researchers analyzed the health

care records of 1.2 million Southern California residents aged 60 and older and found that people who were exposed to higher levels of wildfire smoke had a greater risk of developing

dementia.  

Another study published in 2024 in the journal Neurology found that people with greater exposure to traffic-related air pollution were more likely to have high levels of amyloid plaques in

their brains after they died. These plaques are a hallmark of Alzheimer’s disease.

Inflammation could help explain the emerging link between air pollution and brain health. Some animal studies suggest that “there is a relationship between particulate matter in pollution

and inflammation in the brain,” Bender says. Researchers have also found that tiny pollution particles — the kind you might inhale from smoke or exhaust in the air — can circulate in the

blood and work their way into the brain, where they may cause direct damage.